I did send an email at the weekend about this but haven't heard back so don't know if it got lost somewhere or if the reply landed in my email blackhole or if you've just been too busy doing more important things.
Anyway, I am having trouble placing an order where the order value is less than the store credit I have accumulated. Basically, both paypal and credit card payment methods return an error as the order value is $0 which is invalid.
@Rich
I just sent you an email about this. We will get this sorted out!